Serial Mode

You can explicitly set the workers to 1 either in your config, or in the command that runs the test.

In playwright.config.ts:

export default defineConfig({
  workers: 1,
})

or in the command line:

npx playwright test path/to/test.spec.ts --workers=1

EDIT: I guess you can ignore me, I missed this line: "is there a way to set 1 worker only in a test file?"

I think refactoeric is on the right idea

Having multiple workers for some tests and a single worker for others is complicated.

Option A: Create two separate config files, and run npx playwright test multiple times (in succession), passing the config file with the -c option.

Option B: Use project dependencies to control the order of execution: https://playwright.dev/docs/test-projects#dependencies But this option is only acceptable if you have very few tests that need to run one by one (without parallelism), because you'd need to define a project per serial spec file.

With dependencies looking like project parallelTests Webkit depends on serialTest Webkit project parallelTests Firefox depends on serialTest Webkit project parallelTest Chromium depends on serialTest Webkit project serialTest Webkit depends on serialTest Firefox project serialTest Firefox depends on serialTest Chromium project serialTest Chromium depends on nothing (or depends on setup)

So it's awkward if you want some tests to run in parallel and some running exclusively. Maybe you can avoid it by redesigning the test scenarios and test data to not collide with each other?

I face the same issue. As I understand there isn't a good solution for now. There is a feature request for setting number of workers per project. You can upvote it here: https://github.com/microsoft/playwright/issues/18950